Author Topic: Camshaft selection for 350 build  (Read 2026 times)

Offline krigermoose

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Camshaft selection for 350 build
« on: April 27, 2022, 12:10:07 PM »
Hey all, I'm currently building a 350 for my truck and the most challenging factor for me has been selecting the cam. I will post my specs here and if anyone has a good recommendation I would appreciate it.

Here are my current specs:

1986 GMC C1500 - 3.08 gearing, TH350

010 block, 4 bolt mains, out of a low mileage 74 c20. Ready to be refreshed and built up.

Upcoming machine work (Haven't started it yet): .025 decking, hot tank, hone, wrist pin installation. Maybe take care of the crank and rods a bit as well, not sure on that yet.

Upcoming pistons: Speed-Pro forged pistons 1.563 comp. height, flat top 4 valve reliefs. I went with forged over hyper because it's about $100 extra, worth it to me. Moly rings

Heads: Dart Iron Eagle S/S Iron heads, 165cc intake/65cc exhaust, 210 cfm intake/138 cfm exhaust, 2.020" intake valve/1.600" exhaust valve

Compression: Based on Summit's calculator, around 9.8:1

Using original crank and rods.

Running a Quadrajet, may upgrade to Holley Sniper farther down the line.

I have power brakes and plan on getting A/C working. (I don't know if A/C matters or not, just heard something about it before.)


So I am looking for a flat tappet cam, along with the correct springs and will order a timing gear and chain with it. Nothing crazy, will upgrade torque converter if I should. I am looking for similar performance to a COMP XE262H but I've had some good and bad opinions on it so if anyone has good experience with it let me know.

I just want good low to mid power, something that can cruise on the street but also pushing a bit of extra power.

Online bd

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Re: Camshaft selection for 350 build
« Reply #1 on: April 27, 2022, 03:51:11 PM »
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline VileZambonie

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Re: Camshaft selection for 350 build
« Reply #2 on: April 27, 2022, 05:38:41 PM »
Curious what you are going for on this build.
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74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline krigermoose

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Re: Camshaft selection for 350 build
« Reply #3 on: May 03, 2022, 10:20:57 PM »
I'm just looking for a bit of a bump in power, low to mid end. Something I can have a little fun with. I'm also a sucker for a bit of an idle lope. Just wanna wake up the truck a bit.

Offline JohnnyPopper

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Re: Camshaft selection for 350 build
« Reply #4 on: May 04, 2022, 08:51:37 AM »
Have you thought of making it a 383 stroker?
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline Da67goatman

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Re: Camshaft selection for 350 build
« Reply #5 on: May 04, 2022, 11:37:50 AM »
Idle lope = top end power, low end grunt comes from displacement.  I'd suggest something in the 205-215° @.050 intake duration unless you're going stroker, then maybe as high as a 225°
<Pitcrew>
1989 R2500 Suburban mild 350 TBI 700r4 10.5" 14bolt 4.10 w/ 33s
1992 fullsize Blazer 4x4  35s no lift, 4.10s, Hella driving lights, TJ Flares, Huge bumpers, Snorkel, custom interior

Offline JohnnyPopper

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Re: Camshaft selection for 350 build
« Reply #6 on: May 04, 2022, 06:48:47 PM »
STROKER! STROKER! STROKER!!! 8)
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline krigermoose

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  • 1986 GMC C1500 5.7L
Re: Camshaft selection for 350 build
« Reply #7 on: May 06, 2022, 01:41:53 PM »
Man the stroker is tempting, but my budget it already pretty much at its limit. I wasn't planning on a bore just a hone, and a crank would probably run me a bit. Any ideas for price on that? I already also bought 4.000" forged pistons as well...

Offline JohnnyPopper

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Re: Camshaft selection for 350 build
« Reply #8 on: May 06, 2022, 08:56:19 PM »
Can say what they go for, maybe find a used one that can be ground?

1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline Da67goatman

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Re: Camshaft selection for 350 build
« Reply #9 on: May 07, 2022, 11:24:08 AM »
You do not have to bore it unless the cylinders are out of round or gouged.  You can just put a 3.75" stroke crank in with the 4.00" piston and end up with something like a 378ci.  There may be some clearancing required for the rod bolts, depending on your exact block and rod combo.  Summit sells cast cranks for cheap, you don't need anything extreme for your mild build up.
<Pitcrew>
1989 R2500 Suburban mild 350 TBI 700r4 10.5" 14bolt 4.10 w/ 33s
1992 fullsize Blazer 4x4  35s no lift, 4.10s, Hella driving lights, TJ Flares, Huge bumpers, Snorkel, custom interior

Online bd

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Re: Camshaft selection for 350 build
« Reply #10 on: May 07, 2022, 11:57:08 PM »
You can pair 4.000" pistons from a 350 CID Chevy with a 3.75" stroke crankshaft if you use the shorter 400 CID rods (5.565" center-to-center; C2C).  If you try to use 350 CID rods (5.700" C2C) and pistons with a 3.75" stroke crankshaft, the pistons will protrude proud of the deck.  This is because piston pin height (the distance between the pin axis and the piston crown) is precisely adjusted to the piston stroke, the length of the rod, and the cylinder deck height.  Ideally, for a 383 CID V8 engine, match 4.030" pistons having the appropriate pin height with 6.000" rods and a 3.75" stroke crankshaft.  The longer 6.000" rods decrease side thrusting of the piston skirts into the cylinder walls, equating to less piston rocking and lower friction.  Some block clearancing is generally necessary for a 383 stroker.
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)